Interaction between Iron and Vitamin A in Broilers

Interaction between Iron and Vitamin A in Broilers

^**

Chunshan Zhang*,JunfangJiang,Landi Suo*1 andJianminWei1

** Supported by the Shanxi Province Nature and Science Fund (No. 981086).

* Corresponding Author: Chunshan Zhang. Tel: +86-0354-6288076, Fax: +86-0354-6289295, E-mail: jiang_junfang@sohu.com

1 College of Animal and Veterinary Science, Inner Mongolia Agricultural University Huhhot,010020, P. R. China.

Received September 5, 2002; Accepted November 28, 2002

Animal

Science

Department, Shanxi AgriculturalUniversity, Shanxi030801,

P. R.

China

ABSTRACT:A 3x3 (FexVA) experiment with repeats was designed to study the interaction between iron and vitamin A in broilers.

504 broilers were divided into 9 groups (50% males, 50% femals), each group with 4 repeats. Iron supplemental amount was 0, 30 and 60 mg/kg; Vitamin A supplemental amount was 750, 1,500 and 2,700 lU/kg. Iron concentration in liver, serum, tibia and duodenum and vitamin A concentration in liver and serum were measured, and erythrocyte count was also observed. Results showed with the increase of dietary supplemental iron levels, vitamin A concentration in liver significantly decreased lineally (p<0.05) (0.861, 0.671, 0.639 mg/100 g at the end of 4 th week; 0.900, 0.765, 0.739 mg/100 g at the end of 7th week), and vitamin A concentration in serum significantly increased lineally (p<0.05) (82.725, 97.842, 109.475 卩 g/100 mL at the end of 4th week; 62.288, 91.900, 95.117 卩 g/100 mL at the end of 7th week), meaning iron could promote the mobilization of vitamin A from liver to serum. With the increase of dietary supplemental vitamin A levels, liver iron concentration decreased and serum iron concentration increased, vitamin A could promote the mobilization of iron from liver to blood. Iron concentration in Duodenum and tibia and erythrocyte count increased significantly with higher dietary vitamin A supplementation (p<0.01), vitamin A could promote iron absorption, iron mobilization from liver to target tissues and erythropoiesis. Effects of the interaction between iron and vitamin A on vitamin A concentrations in liver and serum, iron concentration in tibia and erythrocyte count were significant (p<0.05). (Asian-Aust J. Anim Sci 2003. Vol 16, No. 4: 558-564) Key Words : Broilers, Iron, Vitamin A, Interaction

INTRODUCTION

Studies with

children

(Mqjia, 1982; Bloem, 1989;

Wolde-Gebriel,

1993) and pregnant women

(Suharno, 1992) have shown

that vitamin A

deficiency is associated

with impaired iron

status,

while vitamin A supplementation

produced an increase in blood hemoglobin concentrations (Bloem,

1989;

Muhilal, 1988; Mejia, 1988; Bloem, 1990).

The administration

of

vitamin

A in

additiontosupplemental

iron has been

found to enhance the response ofserum

iron

concentration,

transferring

saturation

and

bloodhemoglobin concentration

in

children

and pregnant women with

low

vitamin A and iron

status (Mejia, 1988).

This

suggests that

vitamin A

improves the

utilization of

ingested

iron and

affectsthe

iron

concentrationsof organs.

The mechanism by

which vitamin A affects

iron metabolism is

still

unknown. The fact

that vitamin

A deficiency

in

rats may impairerythropoiesis (Mejia, 1979;

Roodenburg, 1994)

but increased iron

concentrations

in liver

(Mejia,

1979;

Stabb, 1984; West, 1988)

and

spleen (Roodenburg,

1994;

Mejia,

1979)

may point to disturbed

iron

transport.

Many

researchers

studied the effects

of vitamin A

on

iron

status

and

the resultsshowed

vitamin A interfered

with

iron

metabolism. There were few studies about the effects

of iron

on

vitamin A

metabolism.The

previous

studieswere all about the mammal. The

interaction

between vitamin A

and iron

in the

poultry

has not yet

been

studied. It was anticipated

that

this study would provide

clues as

to the

interaction

between

vitamin A and iron in

poultry.

MATERIALS AND METHODS

Experimental designand birds

Interactionbetween

Iron and

Vitamin

A in

Broilers was studied using

a 3

x3 factorial

design of

treatment. The experimental design was

a

randomized-block

design.

Four replicates

per

treatment

(50%

males, 50% femals). Factors were dietary

iron and

vitamin

A.

Threesupplemental levels

of iron

added as feed grade

FeSO

⁴・7H2。were

0,

30,

60 g/kg diet.

Three supplemental levels

of

vitamin

A

added

as

palmitateretinylesterwere 750,

1,500,

2,700

IU/kg

diet.

504

one-day-old Avian

broiler

chicks

from

Shan

Xi

China

Tai Co., LTD.

were divided into nine groups

of

56 chicks

each

(14

birds per replicate) in an

experiment lasting 7weeks.

Birds

were

fed a practical diet,

the diet wasformulated accordingto the Chinese

Nutrient

Requirement

of

Broilers (Chinese Academy

of

Agricultural Science,

1998. Table 1).

The

broilers

were caged

in metal

cages painted

with paint,

with

each replicate

in a

two

story

cages.

Feed and

water were provided

for

ad libitum consumption. All chickens were cared

for in

accordance

with

the

University

Council on Animal care guidelines

of

animal welfare.

Blood

was collected in heparinized

orbital

by orbital puncture. Blood sampleswere

collected from

one

bird per

replicate

(4

birds

Table 1. Dietary composition and nutrient levels

Ingredients Compositions (%) Nutrient levels

0-4 week 5-7week 0-4 week 5-7 week

Corn 46.1 60.02 ME, Mcal/kg 3 3.1

Soybean oil 4.1 3.96 CP, % 22.3 20.5

Soybean meal 37.5 20.23 Met+Cys, %

Cottonseed cake 3 5 Lys, % 0.83 0.68

Rapeseed meal 3 5 Calcium, % 1.13 0.94

Fish meal 0.1 2 Available P, % 1 0.9

Meat and Bone meal 4.8 2 Fe tested in basal diet, mg/kg 0.5 0.45

Bone meal - 0.66 Retinol tested in basal diet, IU/kg 231 296

Stone meal 0.36 0.83 1,000 1,000

Met 0.15 0.06

Salt 0.36 0.24

Choline 0.13 0.13

Trace mineral premix1 0.2 0.2

Vitamin premix2 0.02 0.02

1 Mineral composition (mg/kg of diet):copper8mg;manganese 80 mg;zinc 70 mg; iodine0.4mg;selenium 0.2mg.

2 Vitaminsin amounts per kilogram diet: D3 400 IU; E20IU;k3 0.5mg;B1 1.5 mg;B2 3.6 mg; B3 10 mg; B5 3mg;B& 27 mg;B12 0.009mg; B7 0.15 mg;

B11, 0.55mg.

per

treatment, 50% males, 50%

femals)

at

28

days

and

49 days

of

age respectively. Immediately

after

bleedings, the dead

broilers

werecut

open.

The

liver,

duodenum,

and

tibia wereremoved

and

storedat-20°

C until

analysis.

Experimentalparametersmeasured

Determination of iron concentration

:

Liver waswashed

with

saline

(9

g

NaCl/L).

Liver (1

g) and tibia

(1

g)

were dried (100°

C,

12

h) and ashed

(500°

C,

16

h),

then all the

ash

was dissolved

in 1

mL

6

M-HCl

and

diluted

with

demineralizedwater

to

50 mL. Fe was measured by flame atomic

absorption

spectrometry (Modle AA-475, Varian, Springvale, Australia). Serum Fe concentrations was determined spectrophotometrically using

a

commercial

test

kit (Roche

Nederlang,

Mijdrecht, The Netherlands). All analyseswere

carried out singly. Fe

in

tibia

was calculated

as

themean

of left

and

right

tibia.

Determination of retinal concentration

:

Serum

and

Liver retinal

concentration

were measured by reversed phaseHPLCasdescribedbyRoodernburgetal.

(1996).

Determination of RCC

: Blood

erythrocyte

count

was analyzed

with a

blood cell

counter as

described by Han (1995).

Statisticalanalysis

All

the

data

were analyzedstatistically accordingtothe two-way ANOVA

procedure

(SAS. Institute, 1989)

and

the

treatment

meanswere separated byDuncan

’s

multiple

range test.

Statistical significance was at p<0.05

for

all statistical

tests.

RESULTS AND DISCUSSION

Theeffects of irononvitamin A metabolism

Vitamin A concentration in liver and serum

:

The

concentration of liver vitamin A and

the

concentration of

serum vitamin

A

were significantly (p<0.05)

affected

by dietary

supplemental iron

levels at the

end of 4th and

7th

week respectively (Table

2),

and

withtheincrease

of

dietary

iron

levels,

vitamin A concentration

in liver significantly lineally

decreased

(Figure 1),

and vitamin A

concentration

in

serum significantly lineally

increased

(Figure

2).

Munoz’s

study (2000) showed

iron

supplementation significantly

increased

plasma retinal,

retinol binding

protein, Transthyretin,this suggested

iron

couldenhancethe synthesis

of

vitamin

A transport

protein. These

indicated iron promoted

vitamin

A mobilization from liver

to

blood

by enhancing the synthesis

of

vitamin A. Rosale et

al.

(1999) on

young

rats showed

that

liver vitamin A

concentration

was significantly higher

and plasma

retinal

concentration

was significantly

lower when diets lower in iron

were

fed (p<0.05),

suggesting the

lower

dietary

iron

will

impair vitamin A mobilization from liver.

This agreed tothe

result of

this

study.

Schultink (1997) reported that

iron supplementation

raised retinal

of

anaemic

pre-school children.

Schweigert (2000) reported

that iron

supplementation

prevented

the reduction

in

the

concentration of plasma

retinal inpiglets, resulting

in

higherplasmaretinallevels

(p<0.01). All

these studies suggested

that

vitamin

A played

animportantrole

in

mobilizing

iron from

liver

to

blood.

Theeffects of vitamin A onironmetabolism

Table 2. Retinal concentrations in liver (mg/100 g) and serum (卩 g/100 ml)

Supplemental amount At the end of 4th week At the end of 7th weeks

Fe (mg/kg) VA (IU/kg) n Liver (mg/100 g) Serum (ptg/100 ml) Liver (mg/100 g) Serum (ptg/100 ml)

0 750 4 0.679±0. 478bc1 72.4±17.457 0.354±0.099d 55.187±6.978d

0 1,500 4 1.138±0.19a 83.375±16.469 1.128±0.004ab 65.575±12.263cd

0 2,700 4 0.766±0.057abc 92.4±17.429 1.218±0.042a 66.1±8.687cd

30 750 4 0.683±0.156bc 98.1±31.864 0.868±0.064bc 78.2±16.021bc

30 1,500 4 0.543±0.056bc 97.375±18.331 0.738±0.048c 89.025±15.825bc

30 2,700 4 0.787±0.101血 98.05±12.696 0.689±0.143c 108.475±17.205a

60 750 4 0.402±0.025c 82.825±23.054 0.37±0.051d 97.6±12.115b

60 1,500 4 0.625±0.057bc 109.1±1.326 0.758±0.105c 82.975±15.906bc

60 2,700 4 0.89±0.034ab 136.5±37.798 1.089±0.419ab 104.775±12.354a

0 12 0.861a 82.725b 0.9a 62.288b

30 12 0.671b 97.842ab 0.765b 91.9a

60 12 0.639b 109.475a 0.739b 95.117a

750 12 0.588b 84.442b 0.531b 76.996b

1,500 12 0.768a 96.617ab 0.875a 79.192b

2,700 12 0.814a 108.983a 0.998a 93.117a

P-value Fe 0.0142 0.0212 0.043

VA 0.0147 0.037 0.0001

Fe*VA 0.0029 0.2228 0.0001

0.0001 0.0136 0.0137 a-d Means within acolumn withdifferentsuperscripts are significantly different (p<0.05).

1 Treatment Mean±SD.

m( 응 의-

u)uo

믕 블 8 U O

°

Fe (mg/kg)

Figure 1. Retinal concentration in liver.

Duodenum iron concentration

: The iron

concentration

of duodenum

was significantly

affected

by dietary vitamin

A

levels at the

end of 4th week (p<0.05), and with

the increase

of

dietaryvitamin

A

levels, the

iron

concentration

of

duodenumlineally increased (Table3).

Duodenum

isthe primary place to

iron absorption in broilers

(wang, 1996).

These suggested that

vitamin A

could improve iron absorption. The

effect

was

not

significant (p>0.05) at the

end of

7th,

but

duodenum

iron concentration in

the group

with diet lower in vitamin A

was

lower than other

groups.

The

effect of

dietary

vitamin A

levels

on

the iron

(TH001으

)

uo

믕 블

8UO。

Fe (mg/kg)

Figure 2. Retinal concentration in serum

concentration of

duodenum was significantatthe

end of

4th

week

(p<0.05),

while

was not significant atthe

end of

7th

week

(p>0.05). The

reason

may be

that

the ability

of iron

absorption

of broilers

decreases with the age

increasing.

The studies

of

Layrisse (1998)

and

Garcia

(1998)

both showed

vitamin A

might formacomplexwithiron, keeping

it

soluble in the intestinal

lumen and preventing

the inhibitory effects

of

phytates

and

polyphenols

on iron

absorption, so

vitamin

A

can improve

iron

absorption.

Table 3. Fe Concentrations in liver, duodenum (mg/kg) and serum (mg/l)

Supplemental level At the end of 4th week At the end of 7th weeks

Fe mg/kg VA IU/kg n Duodenum Liver Serum Duodenum Liver Serum

0 750 4 185.18

1

24.671 430.78

±

54.79 0.48±0.06 108.58

±

16.25 312.65±21.26 0.73±0.17 0 1,500 4 232.31

±

17.11 340.93±23.08 0.4

±

0.06 107.71±28.98 307.81

±

55.2 0.8

±

0.02 0 2,700 4 273.64

±

39.55 334.22±74.32 0.61±0.13 93.37

±

5.1 289.96

±

36.1 0.73±0.19 30 750 4 195.29

±

59.33 442.42

±

94.57 0.54±0.06 196.34

±

5.38 337.14

±

18.01 0.68±0.14 30 1,500 4 181.19

±

9.77 431.64

±

31.33 0.72±0.14 156.39

±

31.62 304.46

±

38.21 0.92±0.2 30 2,700 4 201.59

±

53.51 363.9

±

75.21 0.67±0.17 194.21

±

19.06 309.28±27.84 0.97±0.13 60 750 4 163.16±72.17 465.65±41.49 0.68±0.14 90.46

±

9.79 447.51

±

35.42 0.87±0.01 60 1,500 4 185.30±48.22 500.01

±

114.2 0.65±0.17 152.02

±

19.08 347

±

34.44 0.87±0.27 60 2,700 4 188.78±77.26 456.44

±

118.4 0.72±0.09 113.18

±

32.68 341.06

±

52.45 0.97±0.31

0 12 230.38a 368.65b 0.5b 103.22b 303.48b 0.761

30 12 192.69ab 412.66ab 0.646a 178.98a 316.96b 0.86

60 12 179.08b 474.04a 0.687a 118.56b 378.53a 0.908

750 12 171.21b 446.29 0.569 125.93 365.77a 0.765

1,500 12 199.6a 424.2 0.596 140.07 319.76b 0.868

2,700 12 221.34a 384.86 0.668 133.59 313.44b 0.894

P-value Fe 0.0483 0.0088 0.0031 0.0001 0.0001 0.1971

VA 0.0331 0.1608 0.1652 0.3019 0.0035 0.2551

Fe*VA 0.5106 0.5427 0.1893 0.0613 0.0877 0.5521

저3 Means within acolumn withdifferentsuperscripts are significantly different (p<0.05).

1 Treatment Mean土SD.

Another

reason

whyvitamin

A

canimprove

iron

absorption maybe

vitamin A

enhances the

growth

of the cells

in

the

epithelial

intestine (Hong, 1994).

Iron concentration in liver and serum

:

The iron

concentration in liver

was significantly(p<0.05) affected by dietary

vitamin A

levelsatthe

end of

7 thweek,

and

serum

iron concentration

was

not

significant (p>0.05) affected at the

end

of

4th or 7th

week,

and with

theincrease

of

dietary vitamin

A

levels,

liver iron concentration

decreased

(Figure 3)

and

serum

iron concentration

increased (Figure

4) (Table

3). And low dietary

vitamin A

levels is

disadvantageous

to

iron

absorption. These facts above indicated theincrease

of liver iron

concentrationwascaused not

through

the increase

of iron

absorption,

but

throughthe inhibition

of

the

iron mobilization from

liverdue to lower dietary vitamin

A

levels. The mechanism how vitamin A willinterfere

with iron mobilization

is

still

unknown. Chan

09

Vitamin A (IU/kg)

5

8

5

7

5

6 o

J

o

xz

o o

o

o

U 읗

30UO0

£

5 5

7

Vitamin A (IU/kg)

----4 th week --■■■■ -7th week

Figure 4. Fe concentration in serum Figure 3. Fe concentration in liver

and

Wolf (1987) reported vitamin

A

was involved in the synthesis

of

the glycosyl moieties

of

the transferring molecule;

so vitamin A

could

affect iron mobilization

from

liver

whentransferring synthesiswas impaired

in

vitaminA deficiency. Moreover, there was

a

hypothesis

that

lower vitamin

A

levels

impair

the

iron utilization in tissues,

resulting

in

the increase

of

liver

iron

concentration.

The

studies

of Beynen

(1992)

and

sjtsma

(1993)

both showed

liver iron

concentration significantly increased

when

rats were given

diet lower

in

vitamin A.

Suharno (1992) reported there was significantly positive correlation between plasmaretinal

and plasma iron in pregnant

women.

These studies supportedthe

result of

this

study.

In this study, the effect

of

vitamin

A on

liver iron

concentration

at the

end of 4th week and

serum iron

concentration

at the

end of 4th and 7th week

were not significant,

it

maybevitamin

A wasn

’t deficient

enough for

boilers. Roodenburg (1996) reported that vitamin A supplementary

effect in vitamin A

deficiency

condition was

different

from

vitamin

A

supplementary

effect

invitaminA adequacy condition.

From

the effects

of

vitamin

A

on the concentration of

iron

in

liver and

serum, we could know vitamin

A

could promote

iron mobilization

from

liver

to

blood

in

boilers.

Tibia iron concentration

: The concentration of

tibia

iron

significantly (p<0.01) increased with the increase of dietary vitamin

A

levels at the

end

of 7th week

(Table

4), thisindicated vitamin

A promoted

tibia

iron

uptake.

Beynen

(1992)

and

Sijtsma (1993)

both reported femur iron

concentration

significantly

decreased in

rats

given

diet

lower in

vitamin

A

(p<0.05). Sijtsma

(1993) pointed out

that

depressed

uptake

of iron

by

bone

marrowwas the primary feature

of

altered

iron

status inratswith marginalvitaminA deficiency.

RCC

: Red

cell count (RCC)was significantly (p<0.01) affectedatthe

end of

4th

and

7thweek,

and

RCC increased significantlywiththeincrease

of

dietary

vitamin A

levels.It suggested vitamin

A

could improve

iron utilization in

erythropoiesis

in bone

marrow.Roodenburg

(1996)

reported vitamin

A

promoted

formation of

blood

red

cell

in

rats. Li (1996) reported vitamin

A

improved hematopoietic microenvironment

of

rats by promoting BMSC (Bone Marrow Stromal Cell) to secrete hematopoietic growth factors (HGF)

and

enhancing

its

adhesive function. The effects

of

vitamin

A on

the amplification

and differentiation of Blood

red cell family early

ancestor

cell (

BFU-E) are

via changing the expression

of

pro-oncogene c-jun, C-fos

mRNA in

BMSC

and

further regulating the

secretion of HGF.

In theeffectsof

vitamin A

on

iron

metabolism, tibia

iron concentration

significantly reduced, RCC significantly decreased

and liver iron concentration

significantly

increased in

groups

given diet lower in vitamin A (Table 3).

Thesefindings suggested

lower

dietaryvitamin

A

decreased the uptake

of iron

by bone

marrow and increased

the

iron

depositinliver.

From

the results

and discussion of

the effects

of

vitamin

A

onIronMetabolism,

it

was concluded

that

the increase

of

Table 4. Iron concentrations in tibia (mg/kg) and RCC (1010/l)

Supplemental level At the end of 4th week At the end of 7th week

Fe mg/kg VA IU/kg n Tibia RCC Tibia RCC

0 750 4 68.432

±

11.7841 90.75±12.5d 32.8

±

1.535de 258.25±19.293

0 1,500 4 84.380

±

14.752 139.5

±

32.675cd 38.44±2.016de 256.025±45.536

0 2,700 4 83.587

±

6.368 194.5

±

36.263cd 77.103

±

0.273bc 270

±

18.165

30 750 4 76.593±20.3 187

±

9.812bc 56.12

±

5.993cd 176.500±20.550

30 1,500 4 79.333

±

19.188 196

±

34.779bc 75.74±4.004bc 231.5±23.216

30 2,700 4 81.785

±

12.805 230.25

±

35.505b 122.28

±

9.871a 246.75±38.586

60 750 4 88.443±27.205 283±23.366a 45.77

±

12.269de 212.5

±

17.078

60 1,500 4 75.745±20.259 225.25±18.945ab 86.608

±

1.579b 216.5±33

60 2,700 4 78.620

±

7.424 244.25±18.661b 22.357±2.307e 240±8.164

0 12 78.8 141.58c 49.448b 261.5a

30 12 79.237 204.42b 84.713a 218.25b

60 12 80.936 250.83a 51.578b 223b

750 12 77.823 186.92b 44.897b 215.75b

1,500 12 79.819 186.92b 66.929a 234.75ab

2,700 12 81.331 223a 73.913a 252.25a

P-value Fe 0.9475 0.0001 0.0001 0.0008

VA 0.3561 0.0028 0.0002 0.0091

Fe*VA 0.8102 0.0002 0.0001 0.1576

a-e Means within acolumnwith different superscripts are significantly different (p<0.05).

1 Treatment Mean土SD.

dietary vitamin

A

levels improved

iron mobilization

from

liver

to target tissues,

iron uptake, utilization in

bone

marrow and

haematopoiesis.

Theeffects of interaction between vitamin A andiron on all indexin the study

Interaction

between Vitamin

A and iron

significantly

affected liver vitamin A

concentrationatthe

end of 4th

and 7

th week

(p<0.01)andserum

vitamin A concentration

at the

end of 7th week

(p<0.05)

(Table

2). The

higher

level of supplemental

iron

(60 mg/kg) actually

resulted in

asimilar vitamin

A concentration in

serum as seen

in

groups

with higher

dose

of supplemental

vitamin

A

(2,700 IU/kg)

(Table

2).

Interaction

between vitamin

A and

iron significantly (p<0.01)

affected

RCCatthe

end of 4th

week.

RCC

was the

highest in

the

group with

supplemental Fe

(60 mg/kg)

xVA (750 IU/kg) at the

end of 4th week and

Fe (0 mg/kg)xVa (2,700 IU/kg) at the

end of 7th

week;

significantly affected

tibia iron concentration

atthe

end

of 7

th week (p<0.01).

Tibia

iron concentration

wasthe highest in the group

with

supplemental Fe (60

mg/kg)

x

V

A

(750

IU/kg) at the

end of 4th week and in

the group

with

supplementalFe (30mg/kg) xVa (2,700IU/kg)atthe

end

of

7th

week. These

results

suggested vitamin

A and

iron improvetheir

utilization in

thebody

of broilers each other.

IMP니CATIONS

This study

indicated iron

improved vitamin A

mobilization from

liver to blood

and vitamin A

improved

iron mobilization

from

liver

to target tissues,

iron

uptake

and

utilization

in bone

marrow,

and

haematopoiesis in broilers.

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